The lens of a human eye is held within a capsular bag positioned behind the iris in the anterior chamber of the eye. When the lens becomes damaged or diseased a common surgical technique is to remove the lens and replace it with an artificial intraocular lens (IOL). Removal of the lens is commonly carried out by phacoemulsification, that is, using a needle to which vibrational electrical energy is transmitted by a phacoemulsification hand piece.
During phacoemulsification, the lens is broken into fragments and the fragments are emulsified and then removed from the capsular bag by aspirating the fragments through a cannula formed as part of the phacoemulsification needle. After the lens has been removed, the capsular bag must be cleaned in order to prepare it for the insertion of an IOL. In particular, epithelial and cortical tissue fragments must be removed from the floor and perimeter of the capsular bag.
Complete removal of the cortex is important for several reasons. If the cortex is not completely removed it may cause post-operative inflammation and an increase in intraocular pressure. Incomplete removal of the cortex may also cause decentration or tilting of the IOL which, in turn, would cause a postoperative refractive error or induced astigmatism. This is especially important if the IOL is a multi-focal type. Incomplete removal of the cortex may also result in the formation of another cataract which would impair vision.
The present invention has a relatively soft exterior cover which terminates in a substantially spherical tip larger in diameter than the needle. The ball-like, or rounded shape of the tip presents a softer surface with no angles to lessen the possibility of injury to the cortex. The tip can be used to polish the anterior capsule to remove fine cortical residue as well as any remaining viscoelastic material present after implanting the lens. To aspirate the viscoelastic material, the tip is introduced beneath the IOL accomplishing aspiration without stressing the capsular bag or the ciliary zonules.
It is common to use an I/A needle which is straight along its entire length in order to effect removal of the tissue fragments. This requires movement of the needle across the floor and around the periphery of the capsular bag, a range of motion to which the straight needle is not particularly well-suited. The prior art demonstrates attempts to solve this problem by using curved or curvable needles which attempt to improve maneuverability within the eye during surgery.
It is also known to provide straight needles with round or rounded tips formed from hard, metallic material, and to place the aspiration port at an angle to the needle's central passage to provide increased maneuverability.
It is also known to use a thermoplastic or compliant insert with a metallic needle and to have the insert terminate in a ball-like or bulbous shape with an aspiration port formed therethrough. Placement of the insert on the interior of the needle reduces the cross-sectional area available for flow at the working end of the needle. The aspiration port can be angled with respect to the central needle passage by forming the metallic needle with a beveled end and inserting a compliant sleeve in the needle opening at the bevel. This arrangement leaves bare the edges surrounding the needle opening, creating possible snagging or abrasive surfaces.
U.S. Pat. No. 6,491,670 (Toth et al) teaches and describes the miniaturized surgical instruments especially useful for the opthalmologic surgical procedures and methods of making the same. Toth et al discloses an aspiration needle having an outer, rigid lumen within which a soft or “compliant” insert is placed. The insert terminates in a tip having a generally bulbous shape and through which a passage is formed that communicates with the interior passage in the hollow cannula.
U.S. Pat. No. 5,527,273 (Manna et al) teaches and describes an ultrasonic lipectomy probe and method for manufacture having a rigid shank terminating in an enlarged tip. The shank has a hollow internal passage and the tip has at least one inlet port that communicates with the internal passage of the shank. Certain of the tips have inlet ports formed at an angle to the shank passage.
U.S. Pat. No. 3,808,093 (Abraham) teaches and describes a surgical tool having an ultrasonically vibrating solid needle terminating in a curvilinear needle tip. The needle is not hollow and does not either aspirate or irrigate.
U.S. Pat. No. 4,767,404 (Renton) teaches and describes a surgical suction device having a perforated sleeve. The device includes a hollow needle terminating in a tip that has multiple vacuum ports formed therethrough, communicating with the hollow interior of the needle.
U.S. Pat. No. 5,180,363 (Idemoto et al) teaches and describes an operation device having a hollow, ultrasonically vibrated needle terminating at a tip with the tip having ports that communicate to the interior passage of the needle. Once such tip is formed in a ball-like shape and has a number of ports formed through the surface of the ball or through the surface of the tip to allow irrigating fluid or cooling fluid to pass therethrough.
U.S. Pat. No. 5,653,724 (Imonti) teaches and describes an angled phacoemulsifier tip consisting of a rigid phacoemulsification needle having a distal end which is angled with respect to the main needle body. The tip is beveled but not shaped.
U.S. Pat. No. 5,741,226 (Strukel et al) teaches and describes a phacoemulsification handpiece, sleeve and tip having a rigid ultrasonically vibrated needle terminating in a tip which has a single aspiration port formed therethrough. The tip is disclosed with various shapes including hemispherical and substantially spherical configurations.
U.S. Pat. No. 5,755,700 (Kritzinger et al) teaches and describes a corneal irrigation cannula and method of using. The cannula terminates in a tip which is larger than the diameter of the cannula and which is flattened and has multiple irrigation ports.
U.S. Pat. No. 5,993,409 (Maaskamp) teaches and describes a needle for surgical use. The needle is a phacoemulsification needle which is hollow and has a distal portion which is angled with respect to the needle body.
U.S. Pat. No. 6,126,629 (Perkins) teaches and describes a multiple port phaco needle having a hollow needle body terminating in a generally hemispherical tip and with multiple aspiration ports.
U.S. Pat. No. 6,159,175 (Strukel) teaches and describes a phaco emulsification handpiece sleeve and tip and which discloses one tip configuration which is generally hemispherical in shape and has an aspiration port formed therethrough.
U.S. Pat. No. 6,299,591 (Banko) teaches and describes a phacoemulsification handpiece and sleeve and tip which discloses a needle tip having a generally hemispherical shape and including an aspiration port.
U.S. Pat. No. 6,533,750 (Sutton et al) teaches and describes a conically shaped phaco tip. A phacoemulsification needle formed from a rigid material has a portion proximate the end of the needle that is angled with respect to the main needle body and which includes an aspiration port.
U.S. Pat. No. 7,037,296 (Kadziauskis) teaches and describes a curved multi-purpose phacoemulsification needle featuring a straight phacoemulsification needle having a rounded tip with a flat surface through which an aspiration port is formed at an angle to the axis of the needle. In one variation, the distal end of the needle is curved with respect to the main needle body.
U.S. Pat. No. 6,958,056 (Kadziauskis et al) teaches and describes teaches and describes a curved multi-purpose phacoemulsification needle featuring a straight phacoemulsification needle having a rounded tip with a flat surface through which an aspiration port is formed at an angle to the axis of the needle.
U.S. Pat. D556,322 (Akahoshi) teaches and describes a tip of a phacoemulsification needle. The tip is formed in a generally spherical shape and has a plurality of ports formed therethrough.
International Publication WO 00/74615 (Maaskamp) teaches and describes a phacoemulsification needle having a rigid hollow needle body through which multiple ports are formed proximate the tip which has a port formed therethrough.
European Patent Application EP 1,707,166 (Ghamnoun) teaches and describes an irrigation tip used with a surgical hand piece. The tip has a portion of which is curved at a single bend.
I have determined that using an outer sleeve or cover made from thermoplastic material over a metallic hollow needle results in an I/A instrument that presents a smooth tip surface for polishing the cortex and also allows the tip to have a port formed therethrough which communicates with the hollow passageway in the metallic needle via a tip passageway. The tip port can be placed at any desired location on the tip and the tip passageway is then extended to meet the needle passageway at an angle.
I have also determined that needles so designed can have straight or curved configurations to allow for selectable maneuverability in use.
While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that this description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures.